Crimping device

ABSTRACT

A crimping system for a prosthetic heart valve comprises an elongate rigid body and a radially flexible, tubular sock. The body has an inner lumen extending along a central longitudinal axis between an insertion end and an outlet end. The inner lumen has a greater diameter at the insertion end than at the outlet end. The sock is configured to receive a radially compressible prosthetic heart valve in a radially expanded state within the sock and to pull the valve through the inner lumen of the rigid body from the insertion end to the outlet end with the sock being positioned between an outer surface of the valve and an inner surface of the rigid body. The valve is radially compressed by the inner surface of the rigid body as the sock pulls the valve along the longitudinal axis toward the outlet end of the lumen.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/558,053, filed Jul. 25, 2012, which claims the benefit of U.S.Provisional Patent Application No. 61/512,267, filed Jul. 27, 2011, allof which are incorporated by reference herein.

FIELD

The present disclosure relates to crimping devices for crimping stents,frames, stented prosthetic valves, and other medical devices from alarger, expanded diameter to a smaller, crimped diameter.

BACKGROUND

A stent is a generally cylindrical prosthesis introduced into a lumen ofa body vessel via a catheterization technique. Stents may beself-expanding or balloon expandable. Stents are typically crimped froman initial relatively large (or expanded) diameter to a smaller, crimpeddiameter prior to advancement to a treatment site in the body. Beforecrimping, a balloon-expandable stent is typically placed over anexpandable balloon on a catheter shaft. In cases where the stent wasmanufactured in its fully crimped diameter, the stent is often expandedand then crimped on the balloon. A crimping device, or crimper, is usedto crimp the stent to its crimped diameter for delivery.

In recent years, a variety of prosthetic valves have been developedwherein a valve structure is mounted on a stent and then delivered to atreatment site via a percutaneous catheterization technique. Prostheticvalves are typically much larger in diameter relative to coronarystents. For example, a typical coronary stent diameter is only 1.5 to4.0 mm in its expanded size, while a stented prosthetic valve diameterwill typically be in the range of about 19 to 29 mm, at least 5 times aslarge as a coronary stent. In another difference, coronary stents arestand-alone devices while, for prosthetic valves, the stent functions asa scaffold to hold the valve structure. The valve structure is typicallymade of biological materials such as pericardium valves or harvestedvalves. For improved function after deployment, it is often desirable topackage and store such valves in the open (i.e., expanded) diameterinside a preserving solution up until the time the valve is mounted on adelivery device for implantation. Using this procedure, it may benecessary to crimp the valve in the operation room a few minutes beforeimplantation, therefore precluding pre-crimping by the manufacturer.Thus many crimping devices are now shipped as a disposable accessoryalong with the valve and delivery system, thus increasing the importanceof portability of such crimping devices.

Generally, conventional crimping devices operate by one of two methods.In one method, a stent is driven through a cone-like surface, whichcompresses the stent to a smaller diameter. For example, a staticconical tube can be passed over a stent, thereby reducing its diameter.While this method can be effective for some stents formed from easilydeformable materials (e.g., Nitinol), it is less effective for stentsformed from more rigid or stiffer materials. Furthermore, even forstents formed from easily deformable materials, the design of the stentcan sometimes prohibit the use of a static conical tube for crimping.For example, strut thickness and other design features of the frame cancreate a high radial force which would prohibit the use of a staticconical tube.

The second method uses crimping jaws to create a cylinder-like surfacethat can change diameter. This method is effective for stents formed ofboth easily deformable materials as well as less deformable materials.One example of such a crimping device is disclosed in U.S. Pat. No.7,530,253 (hereafter “the '253 Patent”), which is incorporated herein byreference. The device disclosed in the '253 Patent uses a spiral trackpositioned around the jaws to drive the crimping jaws in a radialdirection, thus operating in the plane of crimping. The device of the'253 Patent, however, has limited portability, due to increases in itssize and weight when designed for stents of over 29 mm expandeddiameter.

Other conventional devices having crimping jaws use, for example, slopedgrooves in the plane of crimping to drive the jaws, or rotational motionwithin the plane of crimping. Such devices with mechanisms within theplane of motion can disadvantageously be limited in terms of size,weight, crimping strength, mechanical advantage, and control of thecrimping process. Additionally, newer medical devices sometimes containcomponents or features that are not designed to be crimped. Conventionalcrimping devices cannot accommodate such medical devices, because thecrimping devices are simply designed to crimp the entire medical device.There thus remains a need for an improved crimping device that addressesthese and other disadvantages in the prior art and that has improvedportability and a simplified design.

SUMMARY

Embodiments of crimpers, or crimping devices, are disclosed herein. Someembodiments include an array of crimping jaws that radially compress anobject and are driven by a mechanism out of plane with the plane ofcrimping. For example, the crimping jaws can be driven by axial motionthat is perpendicular to the plane of crimping. Disclosed crimpingdevices include a central iris of variable size that can be used tocrimp medical or other devices (e.g., reduce the diameter of a radiallycompressible medical device) or otherwise grip or hold an object inplace.

In one embodiment, a crimping device can include a plurality of crimpingjaws secured to an outer annular frame positioned adjacent an externalsurface of an inner annular frame. The crimping jaws can extend into theinner frame and come together near the middle of the inner frame tosurround a stent, stented prosthetic valve, or other expandable medicaldevice positioned within the central area of the inner frame, with thelongitudinal axis of the stent parallel to the longitudinal axis of theinner frame. Movement of the inner frame with respect to the outer framealong the longitudinal axis of the stent (e.g., perpendicular to theplane of crimping) can cause the crimping jaws to move closer together,thereby reducing the diameter of the stent (e.g., crimping the stent inthe radial direction). Such a crimping device can be configured to allowaccess to the medical device while it is being crimped, thus ensuringproper positioning or alignment within the crimping device, which can beimportant for medical devices having components that are not crimped.

In other embodiments, other out-of-plane surfaces can be utilized toactuate or drive the crimping jaws closer together, rather than theouter surface of an inner frame driving motion of the crimping jaws. Forexample, in one embodiment, a plurality of sloped guiderails andbearings can drive the motion of the crimping jaws. The slopedguiderails can be arranged to form a conical shape, with a guiderailprovided for each of the crimping jaws. A bearing positioned within thecrimping jaw can allow for smooth motion of the guiderails through thecrimping jaws. As the crimping jaws are moved along the slopedguiderails (e.g., in a longitudinal direction), the jaws can move closertogether, thereby being configured to crimp a medical or other device inthe radial direction (e.g., out of plane with the motion along theguiderails).

Other embodiments of crimping devices disclosed herein include afunnel-shaped rigid body having a split or opening between an upper anda lower half of the funnel. For example, in one embodiment, a medicaldevice can be crimped by being moved through the split funnel from afirst, larger end, towards a second, smaller end. In one example,sutures coupled to the medical device can be used to pull the medicaldevice through the split funnel. The split funnel can be configured suchthat at least a portion of its length includes a longitudinal slot,allowing non-crimped components of the medical device to extend throughthe slots. In this manner, a split funnel crimping device can crimp themain body of a medical device while allowing some components, such asanchors, to remain in their original configuration. A transport systemwith longitudinal slots can be used to transport the crimped medicaldevice from the crimping device to a delivery catheter for implantationwithin a patient.

Other exemplary crimping systems disclosed herein comprise afunnel-shaped rigid body and a tubular sock. A medical device is placedwithin the sock and both are pulled through the funnel-shaped device tocause the medical device to be crimped. Optionally, a catheter or othershaft can be positioned within the medical device and the sock such thatthe medical device is crimped onto the catheter as both are pulledthrough the funnel.

Another exemplary crimping device disclosed herein comprises a pluralityof rotating parallel rollers that are forced radially inwardly toward amedical device to crimp the medical device while the medical device iscaused to spin by the rotation of the rollers. The device can includeand outer shell and an inner shell with in the outer shell andsurrounding the rollers. Relative rotation between the inner and outershells causes the rollers to move radially. The device comprises innerand outer end plates at each end, the inner end plates fixed to theinner shell and the outer end plates fixed to the outer shell. The outerend plates can be parallel and adjacent to each other on each end of thedevice. One of the end plates comprises radial slots and the other endplate comprises sloped slots. The rollers each comprise a center pinwith plural disks mounted thereon and spaced apart by gaps about thesame width as the disks. The ends of each pin extend through the radialslots and the sloped slots. Relative rotation of the inner end plate andthe outer end plate causes the pins to move along the slots and causesthe rollers to move radially inwardly or outwardly to crimp a medicaldevice. The rollers are also caused to rotate while they are movingradially inwardly such that the medical device spins while it is beingcrimped.

The foregoing and other features and advantages of the invention willbecome more apparent from the following detailed description, whichproceeds with reference to the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of one embodiment of a crimper accordingto the present disclosure.

FIG. 2 shows a side elevation view of the crimper of FIG. 1 in a firstposition, corresponding to an open configuration.

FIG. 3 shows a side elevation view of the crimper of FIG. 1 in a secondposition, corresponding to a closed configuration.

FIG. 4 shows a cross-section view of the crimper of FIG. 2, taken alongsection line 4-4 in FIG. 2.

FIG. 5 shows a cross-section view of the crimper of FIG. 3, taken alongsection line 5-5 in FIG. 3.

FIG. 6 shows a perspective view of the back of another embodiment of acrimping device mounted on a stand and base according to the presentdisclosure.

FIG. 7 shows a perspective view of the front of the crimping device ofFIG. 6.

FIG. 8 shows a top view of the crimping device of FIG. 6.

FIG. 9 shows an elevation view of the crimping device of FIG. 6.

FIG. 10 shows a side elevation view of the funnel of the crimping deviceof FIG. 6.

FIG. 11 shows the stand of the crimping device of FIG. 6.

FIG. 12 shows a schematic view of one embodiment of a transport devicefor transporting a medical device crimped in the crimping devicesaccording to the present disclosure.

FIG. 13 shows one example of a medical device with sutures to aid inguiding the medical device through a crimping device.

FIG. 14 shows a schematic view of one embodiment of a pushing tool,transport device, and delivery system.

FIG. 15 shows a side elevation view of one embodiment of a stentedprosthetic valve.

FIG. 16 shows the stent prosthetic valve of FIG. 15, rotated ninetydegrees about the longitudinal axis.

FIG. 17 shows a side elevation view of one embodiment of a stent framefor use with a prosthetic valve, in an expanded configuration.

FIG. 18 shows the stent frame of FIG. 17 in a radially compressedconfiguration.

FIG. 19 shows the stented prosthetic valve of FIGS. 15-16 being crimpedin the crimping device of FIGS. 6-9.

FIG. 20 shows an exemplary embodiment of a delivery system fordelivering and implanting a prosthetic valve at a native mitral valveregion of the heart.

FIG. 21 is a detailed view of the distal portion of the delivery systemof FIG. 20.

FIG. 22 is a perspective view of another embodiment of a crimpingdevice.

FIG. 23 is another perspective view of the crimping device of FIG. 22.

FIG. 24 is a front elevation view of the crimping device of FIG. 22,with part of an outer frame removed to show additional structure.

FIG. 25 is a partial perspective view of the crimping device of FIG. 22,with one of the jaw tops removed.

FIG. 26 is a cross-sectional side view of an exemplary embodiment of afunnel-shaped crimping device.

FIG. 27 is an end view of the crimping device of FIG. 26.

FIG. 28A is a cross-sectional side view of the crimping device of FIG.26 with an exemplary catheter and tube sock positioned within thecrimping device and an exemplary stent positioned around the catheterprior to crimping the stent.

FIG. 28B is a cross-sectional side view of the crimping device of FIG.28A with the stent positioned between the catheter and the stent withina cylindrical portion of the crimping device.

FIG. 28C is a cross-sectional side view of the crimping device of FIG.28A with the stent crimped onto the catheter after having passes throughthe crimping device.

FIG. 29 is a perspective view of another exemplary crimping device.

FIG. 30 is a perspective view of the crimping device of FIG. 29 with anouter shell removed.

FIG. 31 is a perspective view of the crimping device of FIG. 29 withboth an outer shell and an inner shell removed.

FIG. 32 is an end view of the crimping device of FIG. 29 in a radiallyexpanded state.

FIG. 33 is a cross-sectional side view of a portion of the crimpingdevice of FIG. 29 in the radially expanded state.

FIG. 34 is an end view of the crimping device of FIG. 29 in a radiallycontracted state.

FIG. 35 is a cross-sectional side view of a portion of the crimpingdevice of FIG. 29 in the radially contracted state.

FIG. 36 is an end view of an alternative embodiment of the crimpingdevice of FIG. 29.

FIGS. 37A, 37B, 38A and 38B show an alternative configuration for aninterface between roller pins and sloped slots of the crimping device ofFIG. 29.

DETAILED DESCRIPTION

As used in this application and in the claims, the singular forms “a,”“an,” and “the” include the plural forms unless the context clearlydictates otherwise. Additionally, the term “includes” means “comprises.”Although the operations of exemplary embodiments of the disclosed methodmay be described in a particular, sequential order for convenientpresentation, it should be understood that the disclosed embodiments canencompass an order of operations other than the particular, sequentialorder disclosed. For example, operations described sequentially may insome cases be rearranged or performed concurrently. Further,descriptions and disclosures provided in association with one particularembodiment are not limited to that embodiment, and may be applied to anyembodiment disclosed herein. Moreover, for the sake of simplicity, theattached figures may not show the various ways in which the disclosedsystem, method, and apparatus can be used in combination with othersystems, methods, and apparatuses.

FIGS. 1-5 show one embodiment of a crimper, or crimping device, 100 thatcan be used to crimp (e.g., reduce the diameter of) a medical device,such as a stent, frame, or prosthetic valve, or a similar object. Unlessotherwise stated, the terms stent, frame, prosthetic valve, and similarterms are used interchangeably herein to refer to all types of medicaldevices that can be crimped. The crimping device 100 can be used tocrimp a medical device from a larger, expanded diameter, to a smaller,crimped diameter suitable for delivery to a treatment site within apatient (e.g., via percutaneous delivery).

As best seen in FIGS. 1-3, the crimping device 100 can include an outerframe, such as a stand, 102 and an inner frame, or driver, such as acone, 104. The outer frame 102 can be configured to support the cone 104and a plurality of crimping jaws 108 (FIGS. 4-5). The cone 104 can beconfigured to move with respect to the outer frame 102 in the directionsindicated by double-headed arrow 106 (e.g., back and forth along thelongitudinal central axis X of the cone 104). Such motion of the cone104 can cause radial crimping of a medical device positioned within theportions of the crimping jaws 108 that extend into the interior of thecone 104 (FIGS. 4-5) and that are arranged about the axis X in a planeperpendicular to the X axis. Thus, the crimping jaws 108 are driven by amechanism having motion out of a plane of crimping; in this example,movement of the cone 104 is perpendicular to a crimping plane and thedirection of the radial crimping force applied by jaws 108 to themedical device.

The crimping jaws 108 define a variable-sized iris or aperture betweentheir inner ends 126. The variable-sized aperture can vary between alarger diameter (d_(exp)) that can accommodate a stented prostheticvalve in an original, expanded configuration and a smaller diameter(d_(crimp)) that corresponds with the desired crimped delivery diameterof the stented prosthetic valve. The inner portion of the crimping jaws108 can be surrounded by the outer frame 102 such that the outer framedefines a generally cylindrical cavity therewithin that constrains thecrimping jaws 108.

Still with reference with FIGS. 1-3, the outer frame 102 can be, forexample, a 12-sided polygon shaped stationary stand. In otherembodiments, outer frame 102 can be substantially circular or can haveother suitable shapes as well. The outer frame 102 can be annular, suchthat it has a central hole or opening 110 through which the cone 104 canmove. As shown in FIG. 1, the central opening 110 of the outer frame 102can have a “diameter” or greatest dimension of d_(in). The dimensiond_(in) can be at least as great as the maximum outer diameter d_(max) ofthe cone 104 such that the opening 110 of the outer frame 102 is largeenough such that the cone 104 can slide back and forth through the outerframe 102. When positioned as shown in FIG. 1, there may be asubstantial gap between the external surface 112 of the cone 104 and theouter frame 102, due to the difference between the minimum diameterd_(min) of the cone 104 and the maximum diameter d_(max) of the cone104.

The cone 104 can comprise a frustoconical annular body and a plurality(e.g., equal to the number of jaws) of jaw guides, such as slots 114,extending from near a first cone end portion 116 adjacent d_(max) tonear a second cone end portion 118 adjacent d_(min). As shown in FIGS.4-5, the slots 114 can essentially guide the cone 104 as it movesthrough the outer frame 102, due to extension portions 120 of thecrimping jaws 108 that extend from inner portions 128 of the jaws 108through the slots 114 and into corresponding receiving holes, or jawsupport holes, 122 formed in the outer frame 102. As best seen in FIGS.4-5, the extension portions 120 of each crimping jaw 108 can comprise anengagement portion 121 that extends through a corresponding slot 114 inthe cone 104 and an outer portion 124 that aligns with a correspondingreceiving hole 122 in the outer frame 102. The outer portion 124 of thejaw 108 can comprise an enlarged portion disposed within a correspondingreceiving hole 122 in the outer frame 102.

As the cone 104 is moved axially with respect to the outer frame 102,the engagement portion 121 of each of the crimping jaw extensions 120slides within its respective cone slot 114. The design of the crimpingjaws 108 (e.g., with a narrow engagement portion 121, a widened innerportion 128 positioned adjacent the interior of the cone 104, and awidened outer portion 124 positioned adjacent the exterior of the cone104 and inside the receiving holes 122 of the outer frame 102) forcesthe crimping jaws' inner ends 126 to move closer together as the jawextensions 120 slide through the cone slots, thus reducing thevariable-sized aperture formed by the inner ends 126 of the crimpingjaws.

In this manner, movement of the cone 104 from an original configuration(FIG. 4) to a crimping configuration (FIG. 5) can cause the crimpingjaws 108 to move from an original configuration accommodating a medicaldevice having an expanded diameter d_(exp) (FIG. 4) to a crimpingconfiguration that crimps the medical device to a crimped diameterd_(crimp) (FIG. 5). In some embodiments, the crimping device 100 can beused to crimp a medical device directly onto a delivery system. Forexample, crimping device 100 can crimp a balloon-expandable stent orstented prosthetic valve (e.g., a prosthetic heart valve comprising aballoon-expandable metal stent and tissue leaflets supported by thestent) directly onto an inflatable balloon mounted on a deliverycatheter. In other embodiments, the crimping device 100 can crimp aself-expandable medical device directly onto a delivery system. In someembodiments, the crimping device 100 can crimp a self-expandable medicaldevice, which can then be moved directly into a transfer system in itscrimped configuration, as described below, for transport to a differentlocation.

The cone 104 can be moved manually (e.g., by hand) in some embodiments.In other embodiments, movement of the cone 104 can be controlled by anautomated or computer-controlled mechanism. Also, radial movement of thejaws 108 can be accomplished by holding the cone 104 stationary andmoving the outer frame 102 relative to the cone. For example, while theembodiment shown in FIGS. 1-5 has been described such that the cone 104is moved with respect to the outer frame 102, the opposite is alsopossible. In other words, in some embodiments, the outer frame 102 canbe moved with respect the cone 104. While the outer frame 102 is notshown with any additional structure or hardware, the outer frame 102 caninclude additional parts or portions that would better configure theouter frame to be placed securely on a surface, such as a table. In someembodiments, the outer frame 102 can comprise a stand that include abase that supports the annular outer frame 102, and/or a clamp or otherdevice that secures the stand to the table or work surface, in order tosubstantially prevent movement of the outer frame 102.

In other embodiments, out-of-plane surfaces other than the outer and/orinner surfaces of a conical inner frame can be utilized to drive thecrimping jaws closer together. For example, the crimping device 200shown in FIGS. 22-25 includes an inner frame, or driver, 203 thatcomprises a plurality of sloped or inclined guiderails 204 that candrive the motion of the crimping jaws 208 via bearings 230 (FIG. 25) atthe engagement portion of the jaws. The sloped guiderails 204 can bearranged to form a conical or frustoconical shape, with a guiderail 204provided for each of the crimping jaws 208. The guiderails 204 can berigidly secured at their opposing ends to a first end portion 216 and asecond end portion 218. A bearing 230 positioned within each crimpingjaw 208 can allow for smooth motion of the guiderails 204 through thecrimping jaws 208. As the crimping jaws 208 are moved along the slopedguiderails 204 (e.g., as the inner frame 203 and the outer frame 202move axially relative to each other), the jaws 208 move radially closertogether, thereby being configured to crimp a medical device in theradial direction (e.g., out of plane with the motion of the inner frame203) within a variable-sized iris or aperture 226.

The crimping device 200 can include an outer frame 202, an inner frame203 comprising a plurality of guiderails 204 arranged in a generallyconical or frustoconical shape, and a plurality of crimping jaws 208.The outer frame 202 can be configured to surround and/or support theinner frame 203 and crimping jaws 208. The outer frame 202 can beconfigured to move relative to the inner frame 203 in the directionsindicated by double-headed arrow 206 (e.g., back and forth along theguiderails 204). Such relative motion between the outer frame 202 andthe inner frame 203 can cause radial crimping of a medical devicepositioned within the crimping jaws 208 that extend into the conicalinterior of the inner frame 203 and that are arranged about the axis X(FIG. 22). Thus, the crimping jaws 208 are driven by a mechanism havingmotion out of a plane of crimping; in this example, relative movementbetween the outer frame 202 and the inner frame 203 is perpendicular toa crimping plane and the direction of the radial crimping force appliedby jaws 208 to the medical device. In some embodiments, the end portions216, 218 and guiderails 204 of the inner frame 203 can be configured tomove together as a unit with respect to a stationary outer frame 202,acting as a driver, in order to actuate the crimping motion of the jaws208, and in other embodiments, the outer frame 202 and jaws 208 can beconfigured to move together as a unit with respect to a stationary innerframe 203 in order to actuate the crimping motion of the jaws 208.

The outer frame 202 can be, for example, a 12-sided polygon shapedannular frame. In other embodiments, outer frame 202 can besubstantially circular or can have other suitable shapes as well. Theouter frame 202 can be annular, such that it has a central hole oropening within which the inner frame 203 and crimping jaws 208 can move.

The guiderails 204 can extend from the first end portion 216 of theinner frame 203 corresponding to a maximum expanded aperture diameter tothe second end portion 218 of the inner frame corresponding to a minimalcrimped aperture diameter. When the outer frame 202 is positionednearest the first end portion 216, the crimping jaws 208 are farthestapart and the variable-sized iris 226 is at an expanded, maximumdiameter. When the outer frame 202 is positioned nearest the second endportion 218, the crimping jaws 208 are closest together and thevariable-sized iris 226 is at a crimped, minimal diameter.

The crimping jaws 208 each can be provided with an end plate 232positioned adjacent the outer frame 202 and mounted to the crimping jaw208 adjacent the guiderails. The guiderails 204 can extend at an anglethrough both the crimping jaws 208 and the end plates 232 (best seen inFIG. 24). A bearing 230 (seen in FIG. 25 where one end plate 232 hasbeen removed to show the underlying structure) can be positioned suchthat it extends at least partially through each respective end plate 232and crimping jaw 208, thereby providing a smooth surface through whicheach respective guiderail 204 can slide. Each respective end plate 232can be secured to the end of a respective jaw 208 (e.g., with screws)such that a respective bearing 230 is held between or within the endplate 232 and the jaw 208.

A first end 238 of each guiderail 204 can be fixedly coupled to thefirst end portion 216, such as by a screw or other fastener, friction,welding, and/or adhesion (not shown). Similarly, a second end 240 ofeach guiderail 204 can be coupled to the second end portion 218, such asby a screw or other fastener, welding, friction, and/or adhesion. Thus,the guiderails 204 can be configured so as to be essentially immobilewith respect to the first and second end portions 216, 218. In thismanner, the guiderails 204 and end portions 216, 218 collectively form arigid inner frame 203 that is configured to move the jaws 208 closertogether and farther apart from each other upon relative longitudinalaxial movement between the inner frame 203 and the jaws 208.

As the inner frame 203 is moved axially relative to the outer frame 202,each of the guiderails 204 slides through its respective bearing 230 ina corresponding crimping jaw 208 and end plate 232. The crimping device200 can additionally include a plurality of radial guiderails 234, suchas outer portions of the jaws, positioned radially perpendicular to thelongitudinal axis X. FIGS. 24-25 show the crimping device 200 with thefirst end portion 216 removed and the outer frame 202 partially cut-awayin order to better show the radial guiderails 234 and their respectiveradial bearings 236, which are secured within radial openings in theouter frame 202 to provide a smooth surface for radial movement of theradial guiderails 234 through the outer frame 202. In some embodiments,the inner end of each radial guiderail 234 can be secured to arespective end plate 232 to prevent longitudinal or angular movement ofthe jaws 208 relative to the outer frame 202 and constrain the motion ofthe crimping jaws 208 in the plane of crimping (e.g., in the radialdirection). The crimping jaws 208 are therefore forced to move radiallycloser together (reducing the size of the iris 226) as the guiderails204 slide through the crimping jaws 208 in a direction along thelongitudinal axis X, causing the outer frame 202 and the second endportion 218 to be moved closer together (FIG. 22). Conversely, as theguiderails 204 are moved in the opposite direction, causing the outerframe 202 and first end portion 216 to be moved closer together, thecrimping jaws 208 are forced to move farther apart (enlarging the sizeof iris 226). One or both of the outer frame 202 and the inner frame 203can be moved manually (e.g., by hand) in some embodiments. In otherembodiments, relative movement between the inner frame 203 and the outerframe can be provided by an electric motor, hydraulics, pneumatics, orequivalent devices. In some embodiments, movement can be controlled byan automated or computer-controlled mechanism.

As compared with the prior art crimping devices, disclosed crimperembodiments can provide several advantages. For example, the slopedguiderails or conical surface (or other sloped surface) can be designedto create a particular mechanical advantage. Because the slope of theguiderails or cone (e.g., the out-of-plane surface) determines themechanical advantage of the crimping device, the guiderails or cone canbe designed with a steeper slope to decrease the mechanical advantage(e.g., require more force to perform the crimping), or it can bedesigned with a gentler or shallower slope to increase the mechanicaladvantage (e.g., reduce the amount of force required to perform thecrimping).

The degree of sloping can also be used to control the precision of thecrimping device in disclosed embodiments. For example, a steeperguiderail or cone slope will require less travel out of the crimpingplane (e.g., less travel along the longitudinal axis of the cone) tocompress the crimping radius a given amount, thereby reducing the amountof precision. On the other hand, reducing the slope of the guiderail orcone can allow for greater travel of the guiderails or cone with respectto the outer frame, and thus greater precision in crimping.

Disclosed embodiments of a crimping device can also increase theportability of such crimping devices, in that they allow for smallercrimping devices for a particular device than prior art crimping deviceswould. For example, for larger medical devices, such as prostheticvalves having an expanded diameter of more than about 29 mm, prior artcrimping devices sized to crimp such valves typically are heavy andlarge, and thus not easily portable because the in-plane mechanismsrequire an in-plane size increase to accommodate larger medical devices.In prior art crimpers, both the diameter of the crimper and the size ofthe handle (to increase the mechanical advantage) had to increase as thediameter of the medical device was increased. By contrast, currentlydisclosed embodiments allow for the increased diameter of the prostheticdevice to be accommodated both in the length of the guiderails or cone(out of the crimping plane) and in the diameter of the crimper, thusleading to less overall size increases and increased portability.

Additionally, while typical prior art crimping devices restrict orseverely limit access to the crimping jaws, currently disclosedembodiments can allow for maximum access to the crimping jaws ifnecessary. This can advantageously allow currently disclosed crimpingdevices to be used with valves or other medical devices having portionsthat are not crimped, or portions that are moved to a delivery stateafter a main body of the medical device is radially crimped. Forexample, a prosthetic mitral valve can include anchors connected to agenerally tubular main body. The access to the fronts and backs of thecrimping jaws provided by the presently disclosed crimping devices canallow for correct positioning of the main body of the valve within thecrimping device such that the anchors (or other appendages) are notcrimped with the main body.

FIGS. 6 to 9 show another embodiment of a crimping device according tothe present disclosure. Crimping device 600 generally consists of astand 602 supported on a base 603, and a split funnel 604. The splitfunnel 604 can crimp a medical device, such as stent frame 638, as thestent frame 638 is moved through the central opening 610 of the splitfunnel 604, from a first, larger funnel end 616 towards a second,smaller funnel end 618. The stent frame 638 can be moved (e.g., pushed,pulled, or otherwise guided) all the way through the split funnel 604(e.g., the stent frame 638 can exit the split funnel 604 at the secondend 618, which corresponds to the smallest diameter of the split funnel604, and therefore also to the crimped diameter of the medical devicecrimped via the crimping device 600). In some embodiments, the stentframe 638 can be the frame of a prosthetic heart valve.

In some embodiments, a portion of the medical device being crimped inthe crimping device 600 can extend through one or more slots 614 formedin the split funnel 604. For example, the split funnel 604 canessentially be a funnel that has been split along a portion of itslength, to form an upper half 642 and a lower half 644, separated by oneor more slots 614. In the example shown in FIGS. 6-9, the split funnel604 has two slots 614, one on either side of the split funnel 614, butmore or fewer slots 614 are also possible. As shown, the slots 614 canextend only along a portion of the length of the split funnel 604. Forexample, the slots 614 in FIGS. 6-9 extend from the second funnel end618 towards the first funnel end 616, but the slots stop before reachingthe first funnel end 616. Thus, a portion of the split funnel 604 can bewhole (e.g., not split) in some embodiments.

The central opening 610 of the split funnel 604 decreases in diameteralong its longitudinal axis X, decreasing from a maximum diameterd_(max) adjacent the first funnel end 616 to a minimum diameter d_(min)adjacent the second funnel end 618 (FIG. 8). The diameter can decreasecontinuously along the length of the split funnel 604 in someembodiments. In some embodiments, the diameter can change (decrease) atdifferent rates at different segments along the length of the splitfunnel 604. As shown in FIGS. 7-8, in some embodiments, the split funnel604 can include one or more portions 646 having a substantially constantdiameter, and one or more portions 648 having a decreasing diameter.

In some instances, the medical device to be crimped by crimping device600 may include portions that are crimped and portions that remain in anexpanded configuration. For these types of medical devices, conventionalcrimping devices cannot be used because they are designed to crimp theentire medical device, and do not allow for portions to remain uncrimped(e.g., expanded). Advantageously, the slots 614 of the crimping device600 can allow for portions of a medical device to remain in an expandedconfiguration, while the rest of the device is crimped. For example, asstent frame 638 is crimped and moved through the split funnel 614, aportion of the stent frame 638 can extend through one or more of theslots 614, and thus not be crimped because those portions extendingthrough the slots 614 are not inside the central opening 610 of thesplit funnel 604, and thus are substantially unaffected by thedecreasing diameter of the split funnel 604. In one embodiment, as shownin FIG. 19, the stent frame 638 can include one or more anchors 656,where the anchors are positioned to extend through the funnel slots 614as the stent frame 638 is moved through the split funnel 604. In thismanner, the main body of the stent frame 638 can be crimped in thecrimping device 600, while the anchors 656 are not directly crimped bythe crimping device 600.

FIG. 13 shows an embodiment of the stent frame 638, with one or moresutures 640 coupled to the stent frame 638. Sutures 640 can be used tofacilitate crimping of the stent frame 638. For example, as shown, thesutures 640 can be quite long, such as several times longer than thestent frame 638 itself. The sutures 640 can be positioned such that theypass through the central opening 610 of the split funnel 604, extendingout of the second funnel end 618, opposite the first funnel 616 wherethe stent frame 638 enters the split funnel 604. The sutures 640 can belong enough such that there is enough length extending out of the secondfunnel end 618 to grasp and pull, thereby pulling the stent frame 638through the split funnel 604. The sutures 640 can be removed once thestent frame 638 has been moved through the crimping device. In someembodiments, such as for self-expanding prosthetic valves, the crimpedmedical device can be pulled through the crimping device 600 and moveddirectly onto a delivery device or into a delivery sheath. In someembodiments, a self-expanding prosthetic valve can be pulled through thecrimping device 600 and moved directly into a transfer system asdescribed below.

The stent frame 638 can be a stent frame for use with a self-expandablestented prosthetic valve, such as the stent prosthetic valve disclosedin U.S. patent application Ser. No. 12/959,292 (hereafter “the '292Application), which is disclosed herein by reference. FIGS. 15-18,further described in the '292 Application, show one embodiment of astented prosthetic valve 1500 having anchors 1556, an atrial sealingmember 1558, and stent frame 638. In particular embodiments, the valve1500 is a prosthetic mitral valve that can be deployed in the nativemitral annulus. The sealing member 1558 can be deployed in the leftatrium and the anchors 1556 can be deployed in the left ventricle behindthe native mitral valve leaflets. The anchors 1556 can extend throughthe slots 614 of the split funnel 604 as the prosthetic valve 1500 ismoved through the crimping device 600, as shown in FIG. 19. In thismanner, the main body of the prosthetic valve 1500 (e.g., the stentframe 638 and the atrial sealing member 1558) can be crimped in thecrimping device 600, while the anchors 1556 remain uncrimped. FIGS.17-18 show one embodiment of a stent frame 638 having anchors 1556before crimping (FIG. 17) and after crimping (FIG. 18) by presentlydisclosed crimping devices. As seen in FIGS. 17-18, the crimping devicecan crimp the main body of the stent frame 638, while the anchors 1556remain in an expanded configuration.

In some embodiments, the anchors 1556 can be compressed separately,after the main body is radially compressed by the crimping device 600and loaded into a delivery sheath. An outer delivery sheath can then beslid over the anchors 1556 to retain them in a compressed position. Thisallows the stented prosthetic valve 1500 disclosed in the '292Application to be deployed in two stages: first the anchors are deployedas the outer delivery sheath is removed, and second the main body isdeployed as the inner delivery sheath is removed.

Returning to FIGS. 6-9, the split funnel 604 can be coupled to a funnelplate 632 (e.g., formed integral with, welded, adhered, fused, orotherwise coupled to) that facilitates coupling to a stand 602 and base603. The base 603 can, for example, be positioned and/or secured (e.g.,clamped) onto a work surface such as a table or other flat surface. Thebase 603 can be configured to support the stand 602 and split funnel 604as a medical device is crimped in the crimping device 600. In someembodiments, as shown in FIGS. 10 and 11, the funnel plate 632 and thestand 602 can each be provided with one or more fastening holes 636. Inthe embodiment shown, the funnel plate 632 and the stand 602 each havefour fastening holes 636. Each fastening hole 636 on the funnel plate632 can be positioned to align with a respective fastening hole 636 onthe stand 602, in order to secure the split funnel 604 to the stand 602and base 603 for operation. Returning to FIGS. 6-9, one or morefasteners (e.g., screws 634) can be used to couple the funnel plate 632to the stand 602.

During use, a medical device that has been crimped often must betransported at least a short distance to a different location, where itwill be loaded onto a delivery system and implanted into a patient.Depending on the characteristics of the particular medical device beingcrimped, in some instances, the medical device may tend todisadvantageously expand again once removed from the crimping device. Inorder to prevent such re-expansion after crimping, a transfer system canbe used to transport the crimped medical device after crimping. FIG. 12shows a schematic, simplified view of one embodiment of a transfersystem 1200 that can be used to transport a crimped medical device andprevent re-expansion. The transfer system 1200 generally can include asupport structure 1202 and a restraint 1204. The restraint 1204 can be agenerally tubular restraint and can include one or more slots 1214separating an upper restraint half 1242 from a lower restraint half1244. The support structure 1202 can be configured to position the upperrestraint half 1242 with respect to the lower restraint half 1244. Thesupport structure 1202 can additionally provide a surface which can beheld during transport.

The transfer system 1200 can be configured to resist any force exertedon it by a crimped medical device tending to re-expand, so as to preventsuch re-expansion of the medical device. In some embodiments, a portionof the crimped medical device can extend through the slots 1214. Forexample, in embodiments where not all portions of a device are crimped,the non-crimped portions of the medical device can extend through theslots 1214 as the otherwise crimped device is being transported. In oneembodiment, the restraint 1204 can include two slots 1214, spaced about180 degrees apart from one another, and can be configured to allow theanchors 1556 of prosthetic valve 1500 (FIGS. 15-16) to extend throughthe slots, while the restraint 1204 retains the crimped configuration ofthe main body of the prosthetic valve.

FIG. 14 shows a schematic representation of the transfer system 1200 ofFIG. 12 in a position to transfer a crimped medical device into adelivery sheath 1454 of a delivery device. A tool, such as a pushingtool 1450, can be moved in the direction of arrow 1452 such that it atleast partially enters the tubular restraint 1204, thereby displacingthe crimped medical device being held within the tubular restraint 1204.A delivery sheath 1454 can be positioned adjacent the transfer system1200, opposite the pushing tool 1450. Thus, as the pushing tool 1450pushes the crimped medical device through the tubular restraint 1204 ofthe transfer system 1200, the crimped medical device can be pusheddirectly into the delivery sheath 1454. In one specific embodiment, thedelivery sheath 1454 can include one or more slots 1414. For example,the delivery sheath 1454 can include two slots 1414, spaced about 180degrees apart, to accommodate the anchors 1556 of prosthetic valve 1500(FIGS. 15-16) which are left uncrimped by the crimping device 600. Anouter delivery sheath can then be placed onto the delivery sheath 1454,thereby compressing the anchors 1556 for delivery.

FIGS. 20-21 illustrate one embodiment of a delivery system 2000 forimplanting a stented prosthetic valve (e.g., valve 1500) that is crimpedby the disclosed crimping devices. The delivery system 2000 can comprisea series of concentric shafts and sheaths aligned about a central axisand slidable relative to one another in the axial directions. Thedelivery system 2000 can comprise a proximal handle portion 2002 forphysician manipulation outside of the body while a distal end portion,or insertion portion, 2004 is inserted into the body.

The delivery system 2000 can comprise an inner shaft 2006 that runs thelength of the delivery system and comprises a lumen through which aguidewire (not shown) can pass. The inner shaft 2006 can be positionedwithin a lumen of a pusher shaft 2010 and can have a length that extendsproximally beyond the proximal end of the pusher shaft and distallybeyond the distal end of the pusher shaft

The delivery system 2000 further comprises an inner sheath 2014positioned concentrically around at least a distal portion of the pushershaft 2010. The inner sheath 2014 is axially slidable relative to thepusher shaft 2010 between a delivery position and a retracted position.In the delivery position, a distal end portion 2016 of the inner sheath2014 is positioned distal to a distal end, or pusher tip 2018, of thepusher shaft 2010. In the delivery position, the distal end portion 2016of the inner sheath 2014 forms an inner cavity that can contain acompressed prosthetic valve 1500. In the retracted position, the distalend 2017 of the inner sheath 2014 is positioned proximal to or alignedaxially with the pusher tip 2018. As the inner sheath 2014 moves fromthe delivery position toward the retracted position (either byretracting the inner sheath 2014 proximally relative to the pusher shaft2010 or advancing the pusher shaft distally relative to the innersheath), the pusher tip 2018 can force the prosthetic valve 1500 out ofthe distal end portion 2016 of the inner sheath.

As shown in FIG. 21, the inner sheath 2014 comprises one or morelongitudinally disposed slots 2028 extending proximally from a distalend 2017 of the inner sheath. These slots 2028 can allow ventricularanchors 1556 of a prosthetic valve 1500 contained within the innersheath 2014 to extend radially outward from the compressed main body ofthe prosthetic valve while the main body is retained in the compressedstate within the inner sheath. In the embodiment shown in FIG. 21, twoslots 2028 are shown oriented on diametrically opposed sides of alongitudinal central axis of the inner sheath 2014. This embodimentcorresponds to the prosthetic valve 1500, which comprises two opposedventricular anchors 1556. In other embodiments, the inner sheath 2014can comprise a different number of slots 2028, for example four slots,that correspond to the number and location of ventricular anchors on aselected prosthetic valve. In some embodiments, such as shown in FIG.21, the proximal end portion 2020 of the each slot 2028 comprises arounded opening that has a greater angular width than the rest of theslot.

An outer sheath 2036 is positioned concentrically around a portion ofthe inner sheath 2014 and is slidable axially relative to the innersheath. The outer sheath 2036 can be positioned to cover at least aportion of the distal end portion 2016 of the inner sheath 2014. In sucha covered position, the ventricular anchors (e.g., anchors 1556 ofprosthetic valve 1500) can be contained between the inner and outersheath. The outer sheath 2036 is in this covered position while theloaded delivery system 2000 is inserted through the body and into theleft ventricle. The outer sheath 2036 can be retracted proximallyrelative to the sheath 2014 to uncover the slots 2028 and allow theventricular anchors 1556 to spring outward through the slots in theinner sheath 2014 during deployment. Alternatively, the inner sheath2014 can be advanced distally relative to the outer sheath 2036 touncover the slots 2028. The inner sheath 2014 can then be retractedrelative to the prosthetic valve 1500 to complete implantation of thevalve 1500. Additional details of delivery system 2000 and othersuitable delivery systems and methods are disclosed in the '292Application.

FIGS. 26-28C show an exemplary embodiment another funnel shaped crimpingdevice 300. The device 300 comprises an annular wall defining an innerlumen that gradually decreases in diameter from an insertion end 302 toan outlet end 304. The lumen comprises a generally cylindrical portion306 adjacent the insertion end 302, and a tapered portion 308 adjacentto the outlet end 304.

As shown in FIGS. 28A-C, the device 300 is used to crimp an annularmedical device (e.g., a stent 314 or a prosthetic heart valve) onto anelongated member (e.g. a catheter 312) using a tubular sock 310. Thesock 310 can comprise a flexible, mesh-type fabric that provides lowfriction between the sock and the inner walls of the device 300. In someembodiments, the sock 310 can comprise polyethylene terephthalate (alsoknown as PET or Dacron®). The sock 310 desirably is capable of expandingand contracting in diameter between at least the greatest diameter ofthe lumen and smallest diameter of the lumen, but has limitedflexibility in the longitudinal direction such that longitudinal tensionon the sock does not elongate the sock substantially. For example, insome embodiments the sock 310 comprises threads or strands runningcircumferentially around the sock that are resiliently stretchable, andthreads or strands running longitudinally along the sock that arerelatively less stretchable. Desirably, the sock 310 has a length thatis greater than the length of the device 300, as shown in FIG. 28A.

To crimp the stent 314 onto the catheter 312, the catheter 312 and thesock 310 are positioned extending through the lumen of the device 300with the catheter 312 positioned within the sock 310 and the stentpositioned in the cylindrical portion 306 of the lumen in its radiallyexpanded state, as shown in FIG. 28B. In some embodiments, the catheter312 is first inserted into the sock 310, then the sock and catheter areinserted through the lumen of the device 300, and then the stent 314 isinserted into the cylindrical portion 306 of the lumen between the sockand the catheter. In other embodiments, the steps used to arrive at theconfiguration shown in FIG. 28 can be performed in a different order.

In some embodiments, the cylindrical portion 306 of the lumen has aslightly larger diameter than the diameter of the stent 314 in itsradially expanded state. In other embodiments, the diameter of thecylindrical portion 306 can be smaller than the maximum diameter of thestent 314 in its radially expanded state, such that the stent ispartially crimped when it is in the cylindrical portion 306. The stentcan be partially crimped by another device before loading it into thecylindrical portion 306. The insertion end 302 of the device 300 can bebeveled or chamfered around the edge of the lumen to help guide thestent 314 into the cylindrical portion 306. In the configuration of FIG.28B, the stent 314 can be positioned on the catheter 312 at a desiredlongitudinal position relative to the catheter where it is desired thatthe stent be located after the stent is crimped onto the catheter.

The device 300 can then be moved longitudinally relative to the stent314 such that the stent travels through the lumen through the taperedportion 308 and out through the outlet end 304 of the device, as shownin FIG. 28C. In some embodiments, the stent 314 can be held in oneposition while the device 300 is moved over the stent. For example, theportions of the sock 310 and/or the catheter 312 that extend from theoutlet end 304 of the lumen can be gripped and held while the device 300is forced to the left in FIG. 28B, moving the tapered portion 308 of thelumen over the stent 314. In other embodiments, the device 300 can beheld in one position while the stent 314 is moved through the lumen. Forexample, the portions of the sock 310 and/or the catheter 312 thatextend from the outlet end 304 of the lumen can be gripped and pulled tothe right in FIG. 28B while the device 300 is held still, pulling thestent 314 and catheter 312 and sock 310 in unison through the taperedportion 308 and out of through the outlet end 304, as shown in FIG. 28C.

The sock 310 can have a first coefficient of friction against the stent314 that is greater than the coefficient of friction between the sockand inner surface of the lumen. This can help prevent the stent 314 frommoving within the sock 310 as the sock slides along the inner surface ofthe lumen. In some embodiments, the outer surface of the sock 310 cancomprise a different material than the inner surface of the sock tocreate or enhance a difference in friction. For example, the outersurface of the sock 310 can be coated with a low-friction material, suchas polytetrafluoroethylene (also known as PTFE or Teflon®). The innersurface of the lumen can also be coated with a low-friction material.

The minimal inner diameter of the lumen adjacent the outlet end 304determines the crimped diameter of the stent after it exits the device300, although in some embodiments the stent 314 can re-expand or recoila small amount after the crimping forces are released. The slope of thetapered portion 308 between the maximum inner diameter at thecylindrical portion 306 and the minimal inner diameter adjacent theoutlet end 304 can be selected to provide a desired mechanical advantagein converting the longitudinal forces into a radial crimping force. Insome embodiments, the slope of the tapered portion 308 can vary alongits length, such as have a more gradual taper adjacent to thecylindrical portion 306 and a steeper taper adjacent to the outlet end304, or vice versa. As the stent slowly advances down the taperedportion 308, the device 300 converts the net longitudinal force betweenthe device 300 and the stent 314 into a radially crimping force thatcrimps the stent onto the catheter 312. The sock 310 can shrink indiameter around the stent without bunching as the stent graduallybecomes crimped moving through the tapered portion 308.

After the stent 314 exits the outlet end 304 of the device 300, the sock310 is removed from the stent and the catheter 312. The sock 310 can bereused to crimp another stent in the device 300. With the stent crimpedonto the catheter, the assembly can be ready for introduction into thebody.

The sock 310 can prevent the device 300 from scratching or damaging thestent 314. Furthermore, the sock 310 can distribute the longitudinalforces over the whole outer surface of the stent instead ofconcentrating the longitudinal forces on one end of the stent, whichwould be the case if the stent were pushed through the lumen with aplunger device. Pulling the stent with the sock rather than pushing thestent with a plunger can also reduce longitudinally compressive forceson the stent, which can damage the stent and can tend to cause the stentto want to expand radially, and can reduce damage to the leading end ofthe stent related to the leading end of the stent catching on the innersurfaces of the device 300.

In some embodiments, an assembly comprising the device 300, the catheter312, the sock 310, and the stent or prosthetic valve 314 can be arrangedin a pre-crimping configuration, such as shown in FIG. 28B, and thenstored for later crimping. For example, the components can bemanufactured and assembled in such a pre-crimping configuration andpackaged in a sterile container, optionally filled with a fluid. A usercan later open the sterile container in a sterile operating room justprior to implantation of the stent into the body, crimp the stent ontothe catheter by moving the stent through the device 300, and thenintroduce the stent and catheter into the body.

The method of crimping a medical device using the crimping device 300and the sock 310 as described above is particularly useful for crimpinga medical device having a plastically expandable metal frame. However,the assembly could be adapted to compress a self-expandable medicaldevice. When crimping a self-expandable medical device, the sock 310 canbe used to pull the medical device outwardly through outlet 304 and intoa delivery sheath of a delivery device.

FIGS. 29-35 show an exemplary embodiment of a crimping device 400 thatcomprises a plurality of rollers 406 for crimping a medical device. Thedevice 400 comprises an outer shell 402 and an inner shell 404 that arerotatable relative to each other about a longitudinal axis, and aplurality of rollers 406 positioned within the inner shell 404.

The outer shell 402 is generally cylindrical and comprises an end plate408 at either end. The end plates 408 each comprise a plurality of slots412 disposed around a central opening 414. In the embodiment shown, theslots 412 are generally arcuate, or banana shaped, though the shape ofthe slots 412 can vary in other embodiments. The number of the slots 412in each end plate 408 is equal to the number of rollers 406 that arepresent, which is four in the illustrated embodiment. The outer shell402 can optionally include a lateral opening 422 between the two endplates 408 to allow access to the inner shell 404.

The inner shell 404 is also generally cylindrical, but slightly smallerin dimension that the outer shell 402 such that the inner shell fitswithin the outer shell with enough room such that the inner and outershells can rotate relative to one another about the longitudinal axis.The inner shell 404 comprises an end plate 410 at either end. Each endplate 410 comprises a plurality of radially extending slots 416 disposedaround a central opening 418. The central opening 418 can be about thesame diameter as the central opening 414 and the central openings 414,418 can be aligned with each other, as shown in FIG. 32. The inner shell404 can further comprise one or more openings 424 between the end plates410 that allow access to the rollers 406.

FIG. 31 shows the crimping device 400 with the cylindrical portions ofthe inner and outer shells 402, 404 removed for purposes ofillustration. In the embodiment shown, the four rollers 406 eachcomprise a pin 420 that extends longitudinally through the roller andprotrudes out either longitudinal end of the roller into the end plates408, 410. Each end of each pin 420 extends through one of the radialslots 416 in an inner end plate 410 and one of the arcuate slots 412 inan outer end plate 408.

As shown in FIGS. 31, 33 and 35, the rollers 406 each comprise a seriesof circular, disk-shaped elements 434 (referred to as disks) positionedalong the pin. Each disk 434 is about the same diameter and the samethickness. Each disk 434 is spaced apart from the adjacent disk(s) by agap having a width that is about the same as, or slightly greater than,the thickness of the disks. The width of the gaps can be selected basedon the geometry of the stent being compressed. For example, the width ofthe gaps can be sufficiently small to prevent portions of the stent frommoving into the gaps when the stent is being compressed. The disks 434can be comprised of a fairly rigid material, such as a polymeric ormetallic material, and can be coated with another material, such acoating that provides lower or higher friction with between the disksand between the disks and a stent, or a coating that reduces scratchingdamage caused by the disks contacting a stent.

In the embodiment shown in FIGS. 29-35, the device 400 has four rollers406 a, 406 b, 406 c, and 406 d that are oriented parallel to one anotherand spaced evenly around the longitudinal center axis of the device. Thefour rollers 406 are constrained by the radial slots 416 such that therollers can move radially inwardly and outwardly relative to the centeraxis, but the four rollers 406 maintain their equal circumferentialspacing. The disks 434 of each roller 406 can be positioned partiallywithin the gaps between the disks of the adjacent rollers, as shown inFIGS. 33 and 35. It is therefore desirable for the device 400 to have aneven number of rollers 406, such as four, six or eight rollers, suchthat each opposing pair of rollers can be symmetrical about the centeraxis while each roller is offset from the two rollers adjacent to it. Inthe illustrated embodiment, opposing rollers 406 a and 406 c aresymmetric about the center axis and opposing rollers 406 b and 406 d aresymmetric about the center axis, but the disks 434 a, 434 c of therollers 406 a, 406 c are longitudinally offset from the disks 434 b, 434d of the rollers 406 b, 406 d by about the width of one of the disks.This offset allows the disks 434 a and 434 c to move into the gapsbetween the disks 434 b and 434 d, and vice versa, when the four rollers406 moved toward the radially contracted configuration shown in FIGS.31, 34 and 35.

FIGS. 32 and 33 show the device 400 in a radially expandedconfiguration. In this state, the pins 420 are positioned at theradially outer ends of the radial slots 416 and at respective first endsof the arcuate slots 412, and the disks 434 of each roller are spacedapart from the disks of the adjacent rollers. In other embodiments, thedisks 434 can remain partially positioned in the gaps between the disksof the adjacent rollers even in the fully radially expanded state, suchthat the rollers are never spaced apart from the adjacent rollers.

The end view of FIG. 32 illustrates that, in the radially expandedconfiguration, the crimping device 400 has an open cylindrical regionextending through the device from the central opening 414 in the endplate 408 at one end of the device 400 to the central opening 414 in theopposing end plate 408 at the other end of the device. The open regionallows for a compressible annular device 430 (e.g. a stent or prostheticvalve) to be inserted through the central openings 414, 418 at one endof the device and into the open region between the four rollers 406. Inthe example of FIG. 32, the stent 430 is positioned around a centralcatheter 432 within the four rollers 406.

In order to crimp the stent 430 onto the catheter 432, the rollers 406are moved radially inwardly in unison, with the outer surfaces of thedisks 434 contacting the stent and applying compressing pressure on thestent until the stent is radially compressed to a desired crimpeddiameter, as shown in FIG. 34.

In order to cause the rollers 406 to move radially inwardly and compressthe stent 430, the inner shell 404 and the outer shell 402 are rotatedrelative to one another about the center axis. The outer end plates 408are fixed to the outer shell 402 and rotate with the outer shell, whilethe inner end plates 410 are fixed to the inner shell 404 and rotatewith the inner shell. As the outer shell 402 and outer end plates 408rotate (clockwise in the view of FIG. 32) relative to the inner shell404 and inner end plates 410, the arcuate slots 412 force the pins 420to move radially inwardly as the pins 420 move along the arcuate slotsfrom the first ends of the arcuate slots (as shown in FIG. 32) towardthe middle of the arcuate slots (as shown in FIG. 34). When the pins 420are positioned at the portion of the arcuate slots that are closest tothe center axis, the rollers 406 are positioned at their closestposition to the center axis and the medical device 430 is radiallycompressed around the catheter 432. As rollers 406 move radiallyinwardly, the disks approach the disks of the adjacent rollers and enterthe gaps therebetween such that the pins 420 can continue to moveradially inwardly to the maximally radially contracted configuration ofFIGS. 34 and 35.

Further rotation of the outer end plates 408 in the same direction(clockwise in FIGS. 32 and 34) relative to the inner end plates 410causes the pins 420 to move toward the other ends of the arcuate slots412, which causes the pins 420 to move radially outwardly along theradial slots 416 and causes the rollers 406 to move radially outwardlyapart from each other back a radially expanded configuration that isequivalent to that shown in FIG. 32. At this point, the crimped medicaldevice 430 (on catheter 432) can be removed from the crimping device 400through openings 414, 418.

Variations of the crimping device 400 can be configured to crimp stentshaving various maximum and minimum diameters. For example, someexemplary stents have a pre-crimping diameter of up to 30 mm or more,and some exemplary stents have a post-crimping diameter of 1.8 mm orless. Some stents can have a difference of 20 mm or more between theirpre-crimping diameter and their post-crimping diameter. To accommodateparticular types of stents, the diameter of the disks 434, the depth ofthe gaps between the disks, and the length and radial positions of theslots 412 and 416 can be selected accordingly. For example, toaccommodate a stent that has a smaller crimped diameter, then device 400can be modified by increasing the diameter of the disks 434 or by movingthe slots 412 and/or the slots 416 radially closer to the center axis,and the opposite modifications can be made for a stent that has a largerfully crimped diameter. In some embodiments, the outer end plates 408and/or the inner end plates 410 can be swapped out to adjust thelocation of the slots 412 and 416. In some embodiments, the radial slots416 can have a radial length that is longer than the actual radialtravel of the pins 420, such that the inner end plates 410 do not needto be adjusted when the outer end plates 408 are adjusted to accommodatea different size of stent.

In some embodiments, the central openings 414, 418 can be sized to limitthe size of the stent that can be inserted into the device 400. This canhelp prevent a stent that is too large from being inserted into thedevice 400 and possibly damaging the device 400 or the stent. In otherembodiments, the outer central opening 414 is sized to limit diameter ofstents that can be inserted into the device 400, while the inner centralopening 418 has a maximum diameter that is large enough to accommodatethe largest diameter of stent that the rest of the device 400 can beused with.

The slots 412 can be any length or shape, straight or arcuate, and whenarcuate, the slots 412 can be concave toward the outer perimeter of thedevice 400 (as in the embodiment 400) or concave toward the center axisof the device. For example, in an alternative embodiment 450 shown inFIG. 36 the slots 440 in the outer end plates are arcuate and concavetoward the center axis. In other embodiments, the slots in the outer endplates can be straight. Assuming that the slots 416 in the inner endplates 410 are straight radial slots, the slots in the outer end platescan have any orientation as long as they have some variation in theradial dimensions along the length of the slot and also have somevariation the circumferential dimension along the length of the slots.It will be appreciated that in alternative embodiments the outer endplates can comprise the straight radial slots while the inner end platescomprise the sloped slots.

The “slope” of the slots in the outer end plate determines themechanical advantage in transferring a net rotational force between theouter and inner shells 402, 404 into radial forces on the rollers 406.The slope of the slots at any given point along the length of the slotis defined as the ratio of the change in the radial dimension to thechange in the circumferential dimension. The slope of the slots canchange along the length of the slots. For example, in the example of thearcuate slots 412, the slope is approximately zero in the middle of theslots (where the pins 420 are located in FIG. 34) and the slopegradually increases toward either end of the slot. A smaller slopeprovides greater mechanical advantage and a greater slope provides lessmechanical advantage.

The slope of the slots in the outer end plates is also related to therate of motion of the rollers 406. A greater slot slope corresponds to arelatively high rate of crimping motion (i.e., movement of the rollers406 in the radial direction) for a given net rotational motion betweenthe inner and outer shells, while a smaller slot slope corresponds to arelatively low rate of crimping motion for the same net rotationalmotion between the inner and outer shells. Thus, the slop of the slotsin the outer end plates can be selected to achieve a desired amount ofcontrol of the crimping motion of the rollers 406. In the exemplaryembodiment of FIGS. 29-35, the arcuate slots 412 decrease in slope fromthe ends of the slots toward the middle of the slots. As the crimpingprocess of the device 400 proceeds from the configuration of FIGS. 32and 33 toward the configuration of FIGS. 34 and 35, the pins 420initially travel along the high slope portion of the slots 412,resulting in a relatively low mechanical advantage and a relatively highrate of motion of the rollers 406 in the radially inward direction. Thiscan be appropriate for the initial crimping of a stent where relativelylower radial force and relatively lower crimping finesse is required.However, as the crimping process proceeds, the slope of the slots 412where the pins 420 are located decreases, resulting in a relatively highmechanical advantage and a relatively lower rate of motion of therollers 406 in the radially inward direction. This can be appropriatefor the final crimping stages where relatively higher radial force isneeded to compress the stent and greater crimping finesse is required toensure that the stent is accurately compressed to a desired minimumdiameter. Furthermore, with the arcuate slots 412, subsequent netrotation between the inner and outer shells in the same direction causesthe pins 420 to move past the middle point of the slots 420 and towardthe other end of the slots, allowing the rollers to move back radiallyoutwardly away from the crimped stent.

In other embodiments, the slots in the outer end plates can have variousother slope profiles. For example, in the embodiment shown in FIG. 36,the slope of the slots 440 is lower in when the rollers are in theradially expanded position and the slope of the slots 440 graduallyincreases toward a maximum slope as the rollers move radially inwardlytoward the fully crimped position shown in FIG. 36. This results in morefinesse and mechanical advantage during the initial crimping stages andless finesse and mechanical advantage during the final crimping stages,which can be desirable for crimping certain types of objects. In otherembodiments, the slots in the outer end plates can have a constantslope.

The outer shell 402 and the inner shell 404 can be rotated relative toeach other in various manners to cause the crimping motion. For example,the inner and outer shells can be manually rotated relative to eachother by an operator directly applying a rotational force to one or bothof the inner and outer shells. In other embodiments, the relativerotation between the inner and outer shells can be automated. Whenmanual or automated, the rate of the relative rotation can be carefullycontrolled throughout the crimping process to provide a desired ratecrimping. In some embodiments, the inner shell 404 can be held stillwhile the outer shell 402 is rotated, and in other embodiments, theouter shell can be held still (such as fixed to a table or support)while the inner shell is rotated. The opening 422 in the outer shell 402(see FIG. 29) can provide access to the inner shell 402 for applyingrotational force to the inner shell and/or can provide a grippinglocation for applying rotational force to the outer shell. The openings424 in the inner shell 404 can provide a gripping location of the innershell for applying a rotational force. In other embodiments, additionalcomponents, such as a lever or handle, can be attached to one or both ofthe shells 402, 404 to facilitate applying rotational forces. In someembodiments, at least one of the outer end plates can comprise acircumferential slot of other opening that allows a lever or handleattached to the inner shell or inner end plate to protrudelongitudinally out through the outer end plate. In some embodiments, ahandle or lever attached to the cylindrical portion of the inner shell404 can protrude radially out through the opening 422 in the outer shell402.

In addition to each roller 406 moving radially inwardly and outwardly inresponse to the relative rotation between the inner and outer shells402, 404, each roller 406 can also be rotated about the center axis ofits respective pin 420 during the crimping process. All of the rollers406 rotate in the same direction, either clockwise or counterclockwisein the view of FIGS. 32 and 34. When the rollers 406 are in contact withthe stent 430, the rotation of the rollers causes the stent and/or thecatheter 432 to rotate about the center axis of the device 400, but inthe opposite direction of the rollers. For example, if the rollers arerotating in the clockwise direction in FIG. 34, the stent 430 and/or thecatheter 432 rotate in the counterclockwise direction. Desirably, all ofthe rollers rotate at the same speed (i.e., the perimeter surfaces ofthe disks 434 move circumferentially at the same speed), such that theycan all contact the rotating stent 430 without slipping.

The rotation of the rollers 406 and the stent 430 during the crimpingprocess helps reduce damage to the stent caused by the contact by theroller, such as scratching and denting, especially when the disks 434are comprised of a relatively hard material. The rotation of the rollers406 allows the radial crimping forces from the rollers on the stent tobe distributed around the outer surface of the stent rather than beingconcentrated at the discrete locations where the rollers contact thestent. Desirably, the rotational speed of the four rollers 406 issufficiently great such that the stent makes at least ¼ of a rotationduring the crimping process, such that the rollers contact the outersurface of the stent around its whole circumference during the crimpingprocess. It can be further desirable for the rotational speed of therollers 406 to be sufficiently great such that the stent makes at leastone full rotation during the crimping process, such that each of therollers contacts the outer surface of the stent around its wholecircumference during the crimping process. It can be even furtherdesirable for the rotational speed of the four rollers 406 to besufficiently great such that the stent makes plural full rotationsduring the crimping process, such that the crimping forces are moreevenly distributed around the circumference of the stent during thecrimping process.

In order to cause the rollers 406 to rotate, rotational forces can beapplied to at least one end of each of the pins 420. This can beaccomplished in any number of manners. In some embodiments (not shown),the pins 420 project out past the outer end plate at one or both ends ofthe device 420 and a drive belt or drive chain is coupled around all ofthe pins to cause them to rotate in the same direction at the samerotational speed. The drive belt or drive chain can be driven by a motoror other drive mechanism.

In some embodiments, rotation of the rollers 406 can be caused by anengagement between the pins 420 and the inner surfaces of the slopedslots (e.g., 412 or 440). The pins 420 can be engaged with the innersurfaces of the sloped slots in such a way that there is no slippagebetween the engaged contact surfaces and the pin is caused to roll alongthe inner surface of the slot as the pin translates along the slot. Inthese embodiments, the rotation of the rollers 406 is caused by, and isfunction of, the relative rotation between the outer and inner shells402, 404. By linking the rotation of the rollers to the radialtranslation of the rollers, an independent drive source is not needed torotate the roller. In addition, the number of rotations each rollermakes, and the number of rotations the stent makes, during the crimpingprocess can be specifically selected and controlled by engaging the pinswith the inner surfaces of the sloped slots.

The pins can be engaged with the inner surfaces of the sloped slotsusing various techniques and/or mechanisms. In some embodiments, thereis sufficient friction between the pins and the inner surfaces of thesloped slots to prevent any sliding between the contacting surfaces andforce the pins to roll along the slots. In other embodiments, each ofthe pins can comprise a plurality of teeth or cogs around thecircumference of the pin at the portion of the pin that is positionedwithin a sloped slot, and the inner surfaces of the sloped slots cancomprise corresponding teeth that mesh with the teeth on the pins toprevent sliding between the contact surfaces and force the pins to rollalong the slots. FIGS. 37 and 38 show examples of such embodiments.

In FIG. 37A, an exemplary sloped slot 460 comprises a row of teeth 462only on the radially outer surface of the slot and a geared pin 464 thatrolls along the teeth 462. In this embodiment, the geared pin 464 iskept urged against the teeth 462 on the radially outer surface of theslot 460 while the geared pin 464 rolls along the slot. When a stent isbeing compressed by the rollers, the stent can exert a radially outwardforce on the rollers 406 that in turn causes the geared pins 464 to beurged radially outwardly against the teeth 464. In some of theseembodiments, the geared pins 464 can remain engaged with the teeth 464even after the stent is compressed and the rollers are moving radiallyoutwardly away from the compressed stent and there is no longer aradially outward force on the rollers. For example, the device caninclude biasing mechanisms, such as springs, that maintain radiallyoutwardly biasing forces on the rollers and pins.

Causing the rollers 406 to rotate is not necessary when the rollers aredisengaged from the stent after the stent is compressed. Thus, inalternative embodiments, as shown in FIG. 37B, the geared pin 464 candisengage from the teeth 462 when the rollers are moving radiallyoutward such that the pins can slide along the slots without having toroll and the rollers are no longer forced to rotate as a function of themotion of the pins along the slots. As shown in FIG. 37B, the geared pin464 can move radially away from the teeth 464 to provide thedisengagement, or in some embodiments (not shown), the teeth 464 and thegeared pins 464 can be configured to allow the rollers to “free spool”or “freewheel” when moving radially outwardly, such as by providing aclutch or other one-way ratcheting mechanism in the geared pin 464.

FIGS. 38A and 38B show another exemplary sloped slot 470 that comprisesteeth 472 on the radially inner surface of the slot as well as teeth 474on the radially outer surface of the slot. A geared pin 476 can beengaged with the teeth 474 on the outer side of the slot 470 when therollers 406 are moving radially inwardly to compress a stent, and thegeared pin 476 can transition to rolling along the teeth 472 on theinner side of the slot when the rollers are moving radially outwardly. Abiasing mechanism can be provided to maintain a radially inward force onthe pins such that, when there is no radially outward force on therollers from a stent, the geared pins 476 are urged toward the teeth 472on the radially inner sides of the slots 470.

Any of the presently disclosed crimping devices can be designed to applyforces such that it evenly reduces the diameter of the device beingcrimped. The crimping devices according to the present disclosure can beused to crimp any medical device that is expandable and compressible.Examples of such expandable medical devices include stented prostheticheart valves, coronary stents, peripheral stents, other stented valves,venous valves, and stent grafts (e.g., endovascular grafts). Typically,medical devices such as prosthetic heart valves (e.g., prosthetic mitralor aortic heart valves) that are designed to be compressed for delivery(e.g., transcatheter delivery) are crimped to a smaller diameter priorto implantation in the body. The crimping devices according to thepresent disclosure can be used to crimp (e.g., reduce the radius of) anysuch device.

The size and proportions of the disclosed crimping devices can beadapted for and scaled to provide a suitable crimping device for anysize medical device. In some embodiments, disclosed crimping devices canbe optimized to crimp a device having a length of less than about 2inches. In some embodiments, disclosed crimping devices can be optimizedto crimp a device having a length of greater than about 2 inches. Insome embodiments, disclosed crimping devices can be optimized to crimp adevice having an expanded diameter of less than about 29 mm. In someembodiments, disclosed crimping devices can be optimized to crimp adevice having an expanded diameter of greater than about 29 mm. In someembodiments, the crimping engagement surfaces can have a thickness thatis approximately equal to the length of the device being crimped. Forexample, in some embodiments, the crimping engagement surfaces cancontact substantially the entire length of the device being crimped. Insome embodiments, the crimping engagement surfaces can have a thicknessthat is greater or less than the length of the device being crimped.

While the above embodiments have been described as being configured forcrimping medical devices, the disclosed embodiments are not limited tosuch uses. Embodiments can be configured to hold a wide range of sizesof different parts in many different applications. For example,disclosed embodiments can be scaled up or down to hold or clamp any sizeof object, from very large to very small objects. Disclosed embodimentscan also generally be used to crimp or crush any deformable objectwithin the crimping jaws.

In view of the many possible embodiments to which the principles of thedisclosure may be applied, it should be recognized that the illustratedembodiments are only preferred examples and should not be taken aslimiting the scope of the disclosure. Rather, the scope of thedisclosure is defined by the following claims. We therefore claim allthat comes within the scope and spirit of these claims.

We claim:
 1. A crimping system for crimping a prosthetic heart valve,the system comprising: an elongate rigid body having an inner lumenextending along a central longitudinal axis between an insertion end andan outlet end, the inner lumen having a greater diameter at theinsertion end than at the outlet end; and a radially flexible, tubularsock configured to receive a radially compressible prosthetic heartvalve in a radially expanded state within the sock and to pull theprosthetic heart valve through the inner lumen of the rigid body fromthe insertion end to the outlet end with the sock being positionedbetween an outer surface of the prosthetic heart valve and an innersurface of the rigid body, wherein the sock has an axial length greaterthan an axial length of the rigid body, and wherein the prosthetic heartvalve is radially compressed by the inner surface of the rigid body asthe sock pulls the prosthetic heart valve along the longitudinal axistoward the outlet end of the lumen.
 2. The crimping system of claim 1,wherein the inner lumen of the rigid body comprises a cylindricalloading portion adjacent to the insertion end and a tapered crimpingportion extending from the loading portion toward the outlet end, theloading portion have an inner diameter slightly larger than an outerdiameter of the prosthetic heart valve in the radially expanded state.3. The crimping system of claim 2, wherein the tapered crimping portioncomprises a first tapered crimping portion adjacent to the loadingportion and a second tapered crimping portion extending from the firsttapered crimping portion toward the outlet end, wherein the firsttapered crimping has a relatively more gradual taper than the secondtapered crimping portion.
 4. The crimping system of claim 1, wherein acoefficient of friction between an outer surface of the sock and theinner surface of the rigid body is less than a coefficient of frictionbetween an inner surface of the sock and an outer surface of theprosthetic heart valve, such that the sock does not move axiallyrelative to the prosthetic heart valve while the sock slides along theinner surface of the rigid body.
 5. The crimping system of claim 4,wherein the outer surface of the sock comprises a first material and theinner surface of the sock comprises a second material.
 6. The crimpingsystem of claim 1, wherein the rigid body and the sock are configured tocrimp the prosthetic heart valve onto a shaft that is moved through thelumen of the rigid body along with the prosthetic heart valve and thesock.
 7. The crimping system of claim 1, wherein the sock comprises amesh fabric that is substantially more flexible in a radially directionthan in a longitudinal direction.
 8. The crimping system of claim 1,wherein the sock comprises polyethylene terephthalate.
 9. The crimpingsystem of claim 1, wherein the sock comprises a plurality of firststrands arranged circumferentially around the sock that are resilientlystretchable and a plurality of second strands arranged circumferentiallyaround the sock that are relatively less stretchable than the firststrands.
 10. A method of crimping a prosthetic heart valve, the methodcomprising: providing an elongate shaft and a radially flexible tubularsock positioned within and extending through a lumen of an elongaterigid body with the sock positioned between the shaft and the rigidbody, the lumen having a diameter that decreases moving axially from aninsertion end to an opposite outlet end, the sock having an axial lengthgreater than an axial length of the rigid body, and wherein a radiallycompressible prosthetic heart valve in a radially expanded state ispositioned between the shaft and the sock and within a loading portionof the lumen adjacent to the insertion end; and pulling the sock throughthe lumen toward the outlet end such that the sock pulls the prostheticheart valve through the lumen from the loading portion, through atapered portion of the lumen, and out of the outlet end, therebycrimping the prosthetic heart valve as it is pulled through the lumen.11. The method of claim 10, wherein the prosthetic heart valve ispositioned around the shaft at a given axial position along the shaft,and wherein the shaft is pulled through the lumen at the same rate asthe prosthetic heart valve such that the prosthetic heart valve iscrimped onto the shaft at the given axial position along the shaft. 12.The method of claim 10, wherein the sock is longer than the lumen suchthat the sock extends from both the insertion end and the outlet end ofthe lumen when the prosthetic heart valve is loaded into the loadingportion of the lumen.
 13. The method of claim 10, wherein the loadingportion of the lumen is generally cylindrical and has an inner diameterabout equal to an outer diameter of the prosthetic heart valve in theradially expanded state.
 14. The method of claim 10, wherein the loadingportion of the lumen is generally cylindrical and has an inner diameterthat is less than the outer diameter of the prosthetic heart valve inthe radially expanded state, and wherein the prosthetic heart valve ispartially crimped before it is positioned within the loading portion ofthe lumen.
 15. The method of claim 10, wherein pulling the sock throughthe lumen comprises holding the sock and the prosthetic heart valveaxially stationary while moving the rigid body axially over the sock andthe prosthetic heart valve.
 16. The method of claim 10, wherein the sockcomprises a mesh fabric that is substantially more flexible in aradially direction than in a longitudinal direction.
 17. The method ofclaim 10, wherein a coefficient of friction between an outer surface ofthe sock and the inner surface of the rigid body is less than acoefficient of friction between an inner surface of the sock and anouter surface of the prosthetic heart valve, such that the sock does notmove axially relative to the prosthetic heart valve while the sock ispulled through the lumen.
 18. The method of claim 10, wherein theloading portion of the lumen is cylindrical and the tapered portion ofthe lumen has a diameter that decreases moving axially from the loadingportion toward the outlet end.
 19. The method of claim 10, wherein thetapered portion of the lumen comprises a first tapered portion adjacentto the loading end having a first tapered diameter that decreases movingaxially from the loading portion toward the outlet end and a secondtapered portion extending from the first tapered portion toward theoutlet end having a second tapered diameter, wherein the first tapereddiameter decreases relatively more gradually than the second tapereddiameter.